One frustration I had in my radio debate with Sean Pitman was that the topic kept changing in such a rapid-fire way that it was not really possible to discuss anything properly. Happily, I have no such restrictions here at the blog! So let’s devote a post or two to clarifying some of the issues that arose during the debate.
One of Pitman’s talking points was the idea that natural selection is not capable in principle of crafting complex biochemical systems. Of course, this is standard fare for ID folks. Pitman made the claim that there is some level of functional complexity beyond which natural selection cannot go. His only actual argument for this was that a mechanism based on variation and selection has only been observed to produce relatively small amounts of complexity (leaving aside for the moment any questions of precisely how we define complexity.)
A lot of ID writing is devoted to putting meat on the bones of this idea. Michael Behe’s notion of “irreducible complexity” and William Dembski’s notion of “complex specified information” were both intended to provide the missing “in principle” argument for why natural selection cannot produce complex systems. In neither case were these authors successful. Among people who understood some biology and mathematics, Behe and Dembski were quite properly laughed at, since their arguments were really quite bad.
There is a lot to be said against Pitman’s view, obviously, and I said some of it during the debate. But there was one point that I think needs to be made more often in discussions of this topic. When it comes to natural selection, his skepticism reaches dizzying heights. He simply will not accept any sort of circumstantial evidence that natural selection not only can, in principle, craft complex systems, but actually has done so in natural history. At one point he chastised me for claiming that it is not possible to do a meaningful probability calculation regarding the ability of natural selection to craft complexity, claiming that this somehow rendered the theory unscientific.
But all that skepticism goes out the window when it comes to whether intelligence can craft living organisms. Or functional universes for that matter.
I pointed this out during the debate. I asked Pitman why all of his skepticism disappears as soon as the question turns to whether intelligent agents can create living organisms equipped with complex systems. We certainly have no experience of such a thing. Human beings possess the highest level of intelligence with which we have actual experience, but creating universes is many orders of magnitude beyond what such intelligence has been seen to accomplish. Why, then, the willingness to ascribe extraordinary creative abilities to intelligence?
During the debate, Pitman started to reply with an analogy. He argued that we know that intelligence can build outboard motors, which resemble things like the bacterial flagellum. This was taken to be some sort of proof of concept for what intelligence can do.
In the context of his earlier claims, though, this argument is absurd. I am certainly persuaded that intelligence can create relatively simple machines like outboard motors. But that is a far cry from creating a living organism equipped with a flagellum, let alone a functional universe. If we are to judge on what has been observed, which Pitman seems keen to do when it comes to natural selection, then we would have to conclude that intelligence is utterly incapable of doing anything close to what ID folks say it can do.
So the situation is this: With regard to natural selection, we start with the fact that there is no theoretical reason why it cannot craft complex systems. Once you grant that selection has been observed to craft small increases in complexity in short periods of time–and how can you not–then it is hard to find an in principle argument for why it can’t craft more complex systems over longer periods of time. We also have the successes of evolutionary algorithms in solving problems in engineering and medicine, as well as computer simulations of evolution, to serve as a proof of concept. Moving on, for many concrete systems we have strong evidence for how they evolved gradually, and the fact that virtually every complex system studied to date shows clear vestiges of its evolutionary past. It is the universal experience of the scientists who do this work that complex biological systems are incomprehesible from the standpoint of engineering, but become comprehensible as soon as their histories are taken into account. And, most persuasive of all, you have the many practical successes of adaptationist reasoning in biology.
ID folks respond to this by folding their arms, shaking their heads, and repeating ad nauseum that we have no evidence that natural selection can do what we say it can do.
But when it comes to intelligence they are willing to make groundless extrapolations from what is seen to occur, and to hypothesize into existence an awesomely powerful supermind that can do just about anything with acts of its will. This they brazenly claim to be clearly the best explanation for the universe and for life, and they accuse scientists of rejecting it only because of their morbid, anti-religious bias.
Charming. Their argument is no better than claiming that since moles are seen to make molehills, mountains must be made by giant moles. But there are no giant moles, and there is no reason to think the ID proponent’s supermind exists either. Personally, I prefer the relentless success of evolutionary biology to the groundless assertions and empty rhetoric of intelligent design.